1. Field of Invention
The present invention relates to a kind of anode material, its preparation method thereof and a dynamic lithium ion battery, and more particularly to a high manganese polycrystalline anode material and its preparation method thereof, and a dynamic lithium ion battery which makes use of the aforesaid material.
2. Description of Related Arts
Recently, dynamic lithium-ion battery has developed at a fast pace. The function, cost and safety of dynamic battery are the major determining factors in development of electric vehicles. Nevertheless, new energy vehicles which involves wind energy, nuclear energy, solar energy and power cycling have never departed from dynamic battery of which any breakthrough in dynamic battery will bring forward the development of a whole new energy chain development and the dynamic battery becomes the energy storage tool for different new energy sources which replaces fuel as the major energy supply for mobile energy. Electric vehicles are the new type of transportation tool which is energy saving and convenience and are recognized by consumer gradually. In 2007, the ownership of electric vehicles in China has exceeded 20 millions which indicated an unprecedented fast development of electric vehicles. However, numerous problems such as safety and environmental issues which are the prioritized issues are co-existed with the development. At present, the electric vehicles in mainland China still utilize lead-acid batteries of which the problems of low density and high pollution are gradually discovered by people. Accordingly, the race of finding new substitutes becomes a new industry direction at worldwide level. Secondly, Ni-MH battery has advantages of mature technology, convenience and low cost in view of purchase and utilization, and low pollution but unavoidable disadvantages of memory effect which poses great inconvenience in utilization. In addition, Ni-MH battery has high self-discharge rate and low specific energy, therefore the Ni-MH battery can only be used as transition product. In view of the existence and development of Li-ion battery which has numerous advantages such as high power, Li-ion battery gradually replaces Ni-MH battery for energy storage. The Li-ion battery has the following characteristics: 1) high operating voltage which is 3.6V or above, which is three times higher compared to Ni-MH battery; 2) small in volume, which is 30% smaller compared to Ni-MH battery; 3) low density, which is 50% lighter compared to Ni-MH battery; 4) high specific energy of 120˜150 wh/kg, which is 2˜3 times higher compared to Cadnium-Nickel battery and is 1˜2 times higher compared to Ni-MH battery; 5) Absence of memory effect.
Lithium cobalt oxide is the earliest anode materials with mature industry standard which has high energy density, good cycle performance but has drawbacks of high cost and low safety which limited its use in mobile battery. Cobalt-Nickel-Manganese anode materials provide advantages of high energy density and superior cycling performance but the problems of safety and cost remain as the obstacles in the application in mobile battery. Nowadays, the research direction of anode materials for dynamic battery is still focused on lithium iron phosphate and lithium manganese. Lithium manganese has the advantages of low cost and high safety level while having problems of poor cycling performance under high temperature and serious problem of self-discharging effect. Even doping of Co, Ni, Mg, Al are applied for modification, the cost has greatly affected its independent application in mobile battery. Cobalt-Nickel-Manganese anode material basically has superior safety level. However, the control of preparation conditions is complicated and therefore the resulting products have low consistency, low energy density while the cost is high. As a result, the application of Cobalt-Nickel-Manganese anode material should be further improved. Accordingly, the research of anode material with low cost, high safety level and high longevity are important to dynamic battery and to the future development of electric vehicle industry.